The Mpumalanga education department is investigating allegations of racism levelled at the principal of Estralita, a school for the mentally disabled in Lydenburg.
The department sprang into action after receiving an anonymous letter containing allegations of racism at the school.
Among other things the letter claims that accommodation at the school is only offered to whites, even those who do not work at the school, while blacks have to find their own accommodation elsewhere.
"The principal's cottage is also rented by an unknown white person who is not employed by the school, and this is against the law," says the letter.
"This is despite the fact that black staff, including the deputy principal, do not have accommodation and no one knows where the rent for the principal's state-funded cottage goes."
It is also alleged that all pupils at the school are forced to take lessons in Afrikaans and all communication is conducted in Afrikaans.
The anonymous letter goes on to say that the school's filing is not the responsibility of the administration clerk but a therapist.
This despite the fact that there are three clerks who "are treated with kid gloves because they are white".
Provincial education department spokesman Jasper Zwane confirmed that the department had received the letter and was investigating the matter.